We plan to analyze the genomes of ecotropic and amphotropic C-type viruses isolated from wild mice of California. We will use RNase T1 fingerprinting and oligonucleotide mapping. Our objectives are to compare the results of these studies with similar studies we have done with other murine C-type viruses and also to obtain information that may be useful in identifying and mapping genes that determine the ability of the ecotropic wild mouse viruses to cause a neurological disease. Towards this end we will also attempt to make recombinants between neurotropic and non-neurotropic C-type viruses.